BEIJING — A Chinese taikonaut stepped outside the Shenzhou 7 spacecraft Saturday and waved a small red Chinese flag at the millions of his countrymen watching on live television and cheering at their nation’s latest conquest.

With the 15-minute spacewalk, China became the third country to accomplish the feat, following the United States and Russia.

“In the vast space, I felt proud of our motherland,” taikonaut Zhai Zhigang told Chinese President Hu Jintao later over a telephone connecting the spacecraft with a control center in Beijing. Hu peppered the taikonaut, as astronauts are known here, with questions about how it felt to be in space, and thanked him for the success of the mission.

During the spacewalk, in which Zhai floated tethered outside the spacecraft, the taikonaut performed some tests on lubricants, but the event seemed to be as much about public relations as science.

Zhai, 41, grew up poor, supported by a mother who sold sunflower seeds at the market — a biography that for many encapsulates the rags-to-riches story of the Chinese nation.

Chinese media boasted that the $4.4 million spacesuit he wore outside the craft was made entirely in China, while two other crew members on the mission wore Russian suits. The spacewalk was the highlight of Shenzhou 7’s 68-hour mission and took place late Saturday afternoon Beijing time.

Many people gathered around large screens, at times cheering proudly, “Jia you!” — literally “add oil” — the same cheer used at the last month’s Olympics and other sporting events.

“This shows how well-developed China is in its high technology,” said Yang Chang, 32, a trader watching on a long-screen television inside a noodle shop.

Cao Qian, 22, a recent university graduate with a degree in electronics and information technology, said he hoped the spacewalk would bolster the sciences in China.

“We have a big population. Our scientists are more into theory than practice. We are still behind many other countries — the United States, Japan, much of Europe” Cao said.